What I said was you cannot use source code under the GPL with proprietary-licensed or closed-source code, but you can do that with BSD licensed code. The latter makes open source code more appealing for integrating with already-proprietary systems because they will not have to re-license their system and/or open the source up for the world to view their trade secrets [or whatever].

Indeed, you are right. That is, because the FSM sees the proprietary computer software as a social problem. Originally, the OSS software has been a marketing campaign for free computer software, but they disagree in the fundamental things.